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author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-07 17:02:58 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-07 17:02:58 -0800 |
commit | 72eb6a791459c87a0340318840bb3bd9252b627b (patch) | |
tree | 3bfb8ad99f9c7e511f37f72d57b56a2cea06d753 /mm/vmstat.c | |
parent | 23d69b09b78c4876e134f104a3814c30747c53f1 (diff) | |
parent | 55ee4ef30241a62b700f79517e6d5ef2ddbefa67 (diff) | |
download | lwn-72eb6a791459c87a0340318840bb3bd9252b627b.tar.gz lwn-72eb6a791459c87a0340318840bb3bd9252b627b.zip |
Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits)
gameport: use this_cpu_read instead of lookup
x86: udelay: Use this_cpu_read to avoid address calculation
x86: Use this_cpu_inc_return for nmi counter
x86: Replace uses of current_cpu_data with this_cpu ops
x86: Use this_cpu_ops to optimize code
vmstat: User per cpu atomics to avoid interrupt disable / enable
irq_work: Use per cpu atomics instead of regular atomics
cpuops: Use cmpxchg for xchg to avoid lock semantics
x86: this_cpu_cmpxchg and this_cpu_xchg operations
percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support
percpu,x86: relocate this_cpu_add_return() and friends
connector: Use this_cpu operations
xen: Use this_cpu_inc_return
taskstats: Use this_cpu_ops
random: Use this_cpu_inc_return
fs: Use this_cpu_inc_return in buffer.c
highmem: Use this_cpu_xx_return() operations
vmstat: Use this_cpu_inc_return for vm statistics
x86: Support for this_cpu_add, sub, dec, inc_return
percpu: Generic support for this_cpu_add, sub, dec, inc_return
...
Fixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c}
as per Tejun.
Diffstat (limited to 'mm/vmstat.c')
-rw-r--r-- | mm/vmstat.c | 149 |
1 files changed, 113 insertions, 36 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c index 33c33e7a0f9b..312d728976f1 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -167,36 +167,24 @@ static void refresh_zone_stat_thresholds(void) void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item, int delta) { - struct per_cpu_pageset *pcp = this_cpu_ptr(zone->pageset); - - s8 *p = pcp->vm_stat_diff + item; + struct per_cpu_pageset __percpu *pcp = zone->pageset; + s8 __percpu *p = pcp->vm_stat_diff + item; long x; + long t; + + x = delta + __this_cpu_read(*p); - x = delta + *p; + t = __this_cpu_read(pcp->stat_threshold); - if (unlikely(x > pcp->stat_threshold || x < -pcp->stat_threshold)) { + if (unlikely(x > t || x < -t)) { zone_page_state_add(x, zone, item); x = 0; } - *p = x; + __this_cpu_write(*p, x); } EXPORT_SYMBOL(__mod_zone_page_state); /* - * For an unknown interrupt state - */ -void mod_zone_page_state(struct zone *zone, enum zone_stat_item item, - int delta) -{ - unsigned long flags; - - local_irq_save(flags); - __mod_zone_page_state(zone, item, delta); - local_irq_restore(flags); -} -EXPORT_SYMBOL(mod_zone_page_state); - -/* * Optimized increment and decrement functions. * * These are only for a single page and therefore can take a struct page * @@ -221,16 +209,17 @@ EXPORT_SYMBOL(mod_zone_page_state); */ void __inc_zone_state(struct zone *zone, enum zone_stat_item item) { - struct per_cpu_pageset *pcp = this_cpu_ptr(zone->pageset); - s8 *p = pcp->vm_stat_diff + item; + struct per_cpu_pageset __percpu *pcp = zone->pageset; + s8 __percpu *p = pcp->vm_stat_diff + item; + s8 v, t; - (*p)++; + v = __this_cpu_inc_return(*p); + t = __this_cpu_read(pcp->stat_threshold); + if (unlikely(v > t)) { + s8 overstep = t >> 1; - if (unlikely(*p > pcp->stat_threshold)) { - int overstep = pcp->stat_threshold / 2; - - zone_page_state_add(*p + overstep, zone, item); - *p = -overstep; + zone_page_state_add(v + overstep, zone, item); + __this_cpu_write(*p, -overstep); } } @@ -242,16 +231,17 @@ EXPORT_SYMBOL(__inc_zone_page_state); void __dec_zone_state(struct zone *zone, enum zone_stat_item item) { - struct per_cpu_pageset *pcp = this_cpu_ptr(zone->pageset); - s8 *p = pcp->vm_stat_diff + item; - - (*p)--; + struct per_cpu_pageset __percpu *pcp = zone->pageset; + s8 __percpu *p = pcp->vm_stat_diff + item; + s8 v, t; - if (unlikely(*p < - pcp->stat_threshold)) { - int overstep = pcp->stat_threshold / 2; + v = __this_cpu_dec_return(*p); + t = __this_cpu_read(pcp->stat_threshold); + if (unlikely(v < - t)) { + s8 overstep = t >> 1; - zone_page_state_add(*p - overstep, zone, item); - *p = overstep; + zone_page_state_add(v - overstep, zone, item); + __this_cpu_write(*p, overstep); } } @@ -261,6 +251,92 @@ void __dec_zone_page_state(struct page *page, enum zone_stat_item item) } EXPORT_SYMBOL(__dec_zone_page_state); +#ifdef CONFIG_CMPXCHG_LOCAL +/* + * If we have cmpxchg_local support then we do not need to incur the overhead + * that comes with local_irq_save/restore if we use this_cpu_cmpxchg. + * + * mod_state() modifies the zone counter state through atomic per cpu + * operations. + * + * Overstep mode specifies how overstep should handled: + * 0 No overstepping + * 1 Overstepping half of threshold + * -1 Overstepping minus half of threshold +*/ +static inline void mod_state(struct zone *zone, + enum zone_stat_item item, int delta, int overstep_mode) +{ + struct per_cpu_pageset __percpu *pcp = zone->pageset; + s8 __percpu *p = pcp->vm_stat_diff + item; + long o, n, t, z; + + do { + z = 0; /* overflow to zone counters */ + + /* + * The fetching of the stat_threshold is racy. We may apply + * a counter threshold to the wrong the cpu if we get + * rescheduled while executing here. However, the following + * will apply the threshold again and therefore bring the + * counter under the threshold. + */ + t = this_cpu_read(pcp->stat_threshold); + + o = this_cpu_read(*p); + n = delta + o; + + if (n > t || n < -t) { + int os = overstep_mode * (t >> 1) ; + + /* Overflow must be added to zone counters */ + z = n + os; + n = -os; + } + } while (this_cpu_cmpxchg(*p, o, n) != o); + + if (z) + zone_page_state_add(z, zone, item); +} + +void mod_zone_page_state(struct zone *zone, enum zone_stat_item item, + int delta) +{ + mod_state(zone, item, delta, 0); +} +EXPORT_SYMBOL(mod_zone_page_state); + +void inc_zone_state(struct zone *zone, enum zone_stat_item item) +{ + mod_state(zone, item, 1, 1); +} + +void inc_zone_page_state(struct page *page, enum zone_stat_item item) +{ + mod_state(page_zone(page), item, 1, 1); +} +EXPORT_SYMBOL(inc_zone_page_state); + +void dec_zone_page_state(struct page *page, enum zone_stat_item item) +{ + mod_state(page_zone(page), item, -1, -1); +} +EXPORT_SYMBOL(dec_zone_page_state); +#else +/* + * Use interrupt disable to serialize counter updates + */ +void mod_zone_page_state(struct zone *zone, enum zone_stat_item item, + int delta) +{ + unsigned long flags; + + local_irq_save(flags); + __mod_zone_page_state(zone, item, delta); + local_irq_restore(flags); +} +EXPORT_SYMBOL(mod_zone_page_state); + void inc_zone_state(struct zone *zone, enum zone_stat_item item) { unsigned long flags; @@ -291,6 +367,7 @@ void dec_zone_page_state(struct page *page, enum zone_stat_item item) local_irq_restore(flags); } EXPORT_SYMBOL(dec_zone_page_state); +#endif /* * Update the zone counters for one cpu. |